TAKING A CLOSER LOOK: ROCK POOLS ON ABACO


Rock Pool, Abaco 2

TAKING A CLOSER LOOK: ROCK POOLS ON ABACO

Here’s a promising-looking rocky outcrop a short distance south of Crossing Rocks. The action of the sea over centuries has eroded and pitted it – ideal for the formation of pools in which marine life can thrive.Rock Pool, Abaco 1

Time to clamber up to see if the theory holds good… the prospects are encouraging. There are certainly plenty of sea urchins here.Rock Pool, Abaco 4

Let’s zoom in on the nearest pool. There are clearly 2 different-coloured sea urchins here, but I’m not sure if that’s an age thing or a species thing. Rock Pool, Abaco 6

Apart from the sea urchins, there are some shells and other things that need a closer look…Rock Pool, Abaco 5

At the bottom of these photos, you can see that a zebra-marked nerite is quite happy to share a hole with an urchin. There are two brownish accretions on or in the rock. My tentative suggestion is that these are the shells of some sort of worm, perhaps petaloconchus.

UPDATE Rick Guest helpfully comments “Yes, it’s quite the invertebrate hotel mostly due to the urchin’s talent for scouring out protective “rooms”. Of interest is the Magpie shell (Livona pica) in frames 4 and 5. The rather ubiquitous Livona’s very thick shell, (Up to 5″ diameter) and ability to withstand most attempts at removal by predators, including Homo sapiens, assures their continued presence on littoral shore lines. They are edible, but not particular tasty to my palet. All these “Condo” residents “party” at night and will even leave the rock in search of food and perhaps romance, so a flash pic of the condo at night would be an interesting contrast to a daylight shot”.ROCK POOLS, ABACO 11

In a snug little cave (top right) just above the water-level of the pool is a primitive-looking chiton, a species that has been around for millions of years. Below, there’s a clearer image of one from a different pool. These creatures always remind me of school projects on prehistoric trilobites.Rock Pool, Abaco 7Rock Pool, Abaco 10

The rough rocky surfaces close to the pool are covered in shells. The stripey nerites are small, the grey shells really are miniature.  They are mostly littorines/ periwinkles and perhaps ceriths, I think.Rock Pool, Abaco 9Rock Pool, Abaco 12

Close-up views of nerites showing their distinctive markings and spiralsRock Pool, Abaco 13Rock Pool, Abaco 14

SEA URCHINS & SEA BISCUITS – BEACHCOMBING TREASURES ON ABACO


SEA URCHINS & SEA BISCUITS – BEACHCOMBING TREASURES ON ABACO 

It’s time we had some more shells and other beach treasures on these pages. In the absence of star Abaco beachcomber and blog-contributor KASIA I have taken a closer look at the Delphi Club collection. This has been casually accumulated by the Club, its members and guests during the past 3 years whenever a good specimen has been encountered, and is displayed in the Great Room. The first items to catch my eye were the ECHINODERMS, a family that includes sea urchins, sand dollars, sea biscuits and star fish. Their sun-bleached tests are often found, though in my limited experience the larger they are, the rarer.  The link above is to the Wiki-blurb, which has the unpromisingly daunting heading  “This article may be too technical for most readers to understand…”. Now there’s a challenge!

First up is a very large SEA URCHIN, a thing of great delicacy and fragility that weighs next to nothing. I have never seen a bigger one. Looking at the fine detail, it is hard to believe that such perfection of symmetry and intricacy can exist in a creature so very painful to tread on. 

This SEA URCHIN is smaller, with more prominent nodules and a much more random pattern – reminiscent of a cartoon of some distant white planet. It has cast a fine knobbly shadow.

SEA BISCUITS have similar five-way symmetry to their first cousins SAND DOLLARS but are generally pebble-shaped rather than disc-shaped. I have included 2 close-ups to show the fine details of the pattern – almost like lace-work

This SEA BISCUIT is a different type, with the 5 radials reaching right round it. For some reason it only has 4 and not 5 small holes (as one might expect) at the centre. Unlike SAND DOLLARS they tend to be more oblong than round.